The present invention is particularly applicable for use in connection with welding wire and, therefore, the invention will be described with particular reference to a payout or retainer ring used with a package containing a large quantity of welding wire stored therein as a coil containing many convolutions formed into layers. However, the invention has broader applications and may be used with any type of wire or other wire-like materials.
It is, of course, well known that welding is an effective method of joining metal components. Further, it is well known that utilizing a welding wire as a consumable electrode in the welding process enhances the weld. Accordingly, it is desirous to package welding wire so that it can be cost effectively utilized. Furthermore, welding applications wherein large quantities of welding wire are consumed necessitate welding wire packages which contain large quantities of a continuous welding wire. Accordingly, large welding wire packages have been created for these applications which allow for a significant amount of welding run time before the operation must be shut down to restring a new package of welding wire. This is particularly important for automated or semi-automated welding operations.
In order to work in connection with the wire feeder of the welder, the welding wire must be dispensed in a non-twisted, non-distorted and non-canted condition which produces a more uniform weld without human attention. It is well known that wire has a tendency to seek a predetermined natural condition which can adversely affect the welding process. Accordingly the wire must be sufficiently controlled by the interaction between the welding wire package and the wire feeder. To help in this respect, the manufacturers of welding wire produce a wire having natural cast wherein if a segment of the wire was laid on the floor, the natural shape of the wire would be essentially a straight line; however, in order to package large quantities of the wire, the wire is coiled into the package which can produce a significant amount of wire distortion and tangling as the wire is dispensed from the package. As a result, it is important to control the payout of the wire from the package in order to reduce twisting, tangling or canting of the welding wire., This condition is worsened with larger welding wire packages which are favored in automated or semi-automated welding.
The payout portion of the welding wire package helps control the outflow of the welding wire from the package without introducing additional distortions in the welding wire to ensure the desired continuous smooth flow of welding wire. Both tangling or breaking of the welding wire can cause significant down time while the damaged wire is removed and the wire is re-fed into the wire feeder. In this respect, when the welding wire is payed out of the welding wire package, it is important that the memory or natural cast of the wire be controlled so that the wire does not tangle. The welding wire package comprises a coil of wire having many layers of wire convolutions laid from the bottom to the top of the package. These convolutions include an inner diameter and an outer diameter wherein the inner diameter is substantially smaller than the width or outer diameter of the welding wire package. The memory or natural cast of the wire causes a constant force in the convolutions of wire which is directed outwardly such that the diameter of the convolutions is under the influence of force to widen. The walls of the welding wire package prevent such widening. However, when the welding wire pays out of the package, the walls of the package loose their influence on the wire and the wire is forced toward its natural cast. This causes the portion of the wire which is being withdrawn from the package to loosen and tend to spring back into the package thereby interfering and possibly becoming tangled with other convolutions of wire. In addition to the natural cast, the wire can have a certain amount of twist which causes the convolutions of welding wire in the coil to spring upwardly.
There are two aspects of controlling the unwinding of wire from a wire coil package. First is to prevent the upward springing of the wire convolutions within the wire coil package. The second is management of the wire as it travels from the wire coil package to the wire feeder so that it doesn't spring back. Controlling the upward springing effect of the wire convolutions is achieved by maintaining the position of the wire convolutions at the top of the wire coil and especially at a point where the upward springing effect is at its greatest which is towards the radially outer portions of the package. With respect to controlling the wire as it travels between the payout and the wire feeder, it has been found that tensioning along with guiding the wire can reduce the twisting and tangling effects. In this respect, by creating a slight tension along with using a guiding mechanism, the wire is controlled as it moves between the wire coil package and the wire feeder and is prevented from springing back into the package.
Payout devices or retainer rings have been utilized to control the spring back and upward springing of the wire and to control the payout of the wire. This is accomplished by positioning the payout or retainer ring on the top of the coil and forcing it downwardly against the natural springing effect of the welding wire. The downward force is either the result of the weight of the retainer ring or a separate force producing member such as an elastic band connected between the retainer ring and the bottom of the package. Further, the optimal downward force during the shipment of the package is typically different than the optimal downward force for the payout of the welding wire. Accordingly, while elastic bands or other straps are utilized to maintain the position of the payout or retainer ring during shipping, the weight of the retainer ring is often used to maintain the position of the payout relative to the wire coil during the payout of the wire.
The outward flow of wire, or payout, is managed by the payout or retainer ring's position on the top of the wire coil which holds the upper layers of the convolutions in place as the wire is withdrawn one convolution at a time. In addition, the payout or retainer ring includes an edge or surface, typically a radially inwardly facing edge or surface, which controls the payout of the wire. In this respect, the wire is pulled from the center of a ring shaped device and engages the radially inwardly facing portion thereof. The retainer ring further includes a mechanism to prevent the wire from springing around the radially outer side of the retainer ring. Prior art retainer rings utilize a unified ring structure which includes resilient members that tightly engage the inner surface of the outer package to protect the outer convolutions of the welding wire coil and prevent the wire from springing around the outside of the retainer ring.